1. Field of the Invention
The present invention relates to a valve cleaning apparatus and method in which impurities are removed from valves without contaminating downstream fabrication equipment. The invention may be employed for easily cleaning valves having a heat resistant, scratch resistant coating such as TEFLON (trademark of Dupont).
2. Background of the Related Art
Acid and corrosive chemicals are generally used for the wet etching and cleaning steps in semiconductor device fabrication. These steps cannot proceed properly in the presence of particles or impurities in the acid or chemicals.
The chemicals used for the wet etching and cleaning steps pass through a TEFLON valve such as a diaphragm valve mounted at one side of a liquid storage tank, before being supplied into the liquid storage tank. A TEFLON diaphragm is provided within the valve, and the valve is opened or closed using nitrogen gas (N.sub.2) supplied under pressure The chemicals in the liquid storage tank are then discharged through a TEFLON valve mounted on the other side of the liquid storage tank, and are sent on to semiconductor device fabrication facilities where the wet etching and cleaning steps are performed.
When a TEFLON valve is initially mounted onto the liquid storage tank, it is cleaned by means of the chemicals from the liquid storage tank which are discharged through the valve for a predetermined period of time. However, metal impurities adhered to TEFLON parts such as the diaphragm are not completely removed by the chemicals, and may then be supplied to semiconductor device fabrication facilities, causing production problems such as inferior etching and incomplete cleaning.